Unless you have a strange love for pyrotechnics, for the love of all that is good and fashionable, turn off your iron! Leaving an iron on can start a fire.
To avoid a flaming disaster, plug your iron into a power strip with a lamp. Always leave the lamp's switch on and use the on/off button on the power strip to turn the lamp off. When the light is off, you can be absolutely sure your iron is, too, because it's in the same strip!